Cincinnati Area Geographic Information System (CAGIS)

Geographic Information System

A successful Geographic Information system (GIS) is built and not bought. This is
because GIS is data-driven and the effective use of GIS relies on accurate and up-to-date
information being available to improve the service efficiency of an organization. Often
this information is dependent on other agencies to create, update and maintain. GIS,
successfully implemented in an organization, is a technology that enables the non-GIS
staff to be more productive and more accurate in performing their daily work, resulting in the
institutionalizing (embedding) of technology in the workflows. This is an incremental
process. CAGIS continues to support and create an environment of trust, success and
credibility to secure long-term commitment and support at all levels of the organization
for change.

CAGIS manages over 200 map information layers with many of them contributed and
maintained by participating agencies. This shared dataset is the underlying foundation
for the integration and coordination framework over which all agency processes are
automated for effective service delivery. This dataset also supports analysis, decision making,
planning, community participation and a host of other services.

What types of GIS data are available through CAGIS?

CAGIS data can be categorized into these general categories, which are made available to the public via digital data or online channels:

Planimetric data – outlines of land features visible from aerial photography, which include building structures, pavement edges, driveways, parking lots, sidewalks, trails, walls and guardrails, poles, rivers and streams, etc.

Underground utility data – water, storm water and sewer utility data are maintained by CAGIS consortium members, data can be obtained only through the Greater Cincinnati Water Works (GCWW) and Metropolitan Sewer District (MSD) on project-by-project basis.

How accurate are CAGIS Data?

All CAGIS data meet or exceed the National Map Accuracy Standards for 1"=100’ base map for both horizontal and vertical accuracy:

Horizontal (positional) – ± 2 foot

Vertical (contour elevation) – ± 1 foot

How are CAGIS data created and maintained?

All CAGIS planimetric data were created using the industrial standard photogrammetric procedures. Utilizing highly specialized hardware and software, visible land features are identified in aerial photography and painstakingly digitized by trained professionals.

Prior to 2011, all CAGIS contour data were captured using stereoscopic triangulation method - the standard process to produce high accuracy elevation contours. In 2011, CAGIS chose LIDAR (Light Detection and Ranging) technology to produce its contours. LIDAR captures "clouds" of elevation points based on which contours are generated.

CAGIS property boundary data are based on professional survey information, the metes and bounds of property surveys are recorded in mapping using coordinate geometry (COGO).

CAGIS also maintains real-time address and street information as part of its geographic information framework that is integrated with all of its enterprise GIS and permitting operations. The address and street layers provide the most complete and up-to-date location information for Hamilton County and for part of the surrounding communities.

How often does CAGIS acquire aerial imageries and what is the latest aerial orthophotography CAGIS provides?

CAGIS acquired its latest aerial imageries in March, 2011. The latest aerial imageries cover the entire Hamilton County and part of Butler, Warren and Clermont counties in Ohio.

What is aerial orthophotography? What are the different types of orthophotography CAGIS offers?

An orthophoto, orthophotography or orthoimage is an aerial photograph geometrically corrected ("orthorectified") such that the scale is uniform: the photo has the same lack of distortion as a map. Unlike an uncorrected aerial photograph, an orthophotograph can be used to measure true distances, because it is an accurate representation of the Earth's surface, having been adjusted for topographic relief, lens distortion, and camera tilt inherited from the aerial photo capturing process.